<%@ page import="edu.ahut.util.Adder" %>

a=<%=request.getParameter("a")%><br/>
b=<%=request.getParameter("b")%><br/>

<%
    int a=0;
    int b=0;
    String sa=request.getParameter("a");
    String sb=request.getParameter("b");
   // if(sa.equals("abc"))//poor
    if("abc".equalsIgnoreCase(sa))//better
    try {
        a = Integer.parseInt(sa);
        b = Integer.parseInt(sb);

    }catch (Exception e){
        response.sendRedirect("add.html");

    }
    session.setAttribute("c", Adder.add(a,b));

%>